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Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 937 records · Page 52Linked to original sources
PubMed1967

The fine structure of embryonic chick skeletal muscle cells differentiated in vitro.

Dissociated myoblasts from 12-day chick embryos were cultured in monolayer, and the differentiation of skeletal muscle cells was studied by electron microscopy. The results have revealed a striking ultrastructural similarity between the in vivo and the in vitro developing muscle, particularly with respect to the myofibrils and sarcoplasmic reticulum. This study demonstrates that all the characteristic organelles of mature skeletal muscle can develop in vitro in the absence of nerves.

Animals↗
PubMedDate not supplied

Clinicopathological characteristics of duodenal microgastrinomas.

Duodenal gastrinomas do not seem to behave as malignantly as sporadic pancreatic gastrinomas. Statistical analysis of 49 patients with sporadic pancreatic gastrinoma and 21 patients with sporadic duodenal gastrinoma reported since 1980 in Japan revealed that the incidence of hepatic metastasis was 57% in patients with sporadic pancreatic gastrinoma and only 9% in patients with sporadic duodenal gastrinoma (p less than 0.01). These findings suggest that there is an essential biological differences between duodenal and pancreatic gastrinoma. Five patients with sporadic duodenal microgastrinoma (tumor diameter less than 5mm) in our hospital had no hepatic metastases; however, 4 patients had lymph node metastases. Immunohistochemical study of 5 sporadic duodenal microgastrinomas and 6 sporadic pancreatic gastrinomas revealed that the sporadic duodenal gastrinomas contained significantly fewer insulin-producing or glucagon-producing cells than sporadic pancreatic gastrinomas. The cellular composition of the metastatic lymph nodes from duodenal microgastrinomas was similar to that of the primary tumor. This difference in cellular composition between the duodenal microgastrinomas and the pancreatic gastrinomas suggests that the process of development and differentiation of gastrinoma cells is different.

Adult↗
PubMedDate not supplied

Color-coded pattern suppresses visual evoked cortical potentials and electroretinograms.

We developed a new visual stimulating system for recording visual evoked cortical potentials and electroretinograms. The stimulus was a color checkerboard, in which each check kept its chromaticity but changed its luminance with its corresponding check. Color-coded pattern stimuli using red and green checks did not produce visual evoked cortical potentials, while yellow checks produced clear responses in a normal subject. Moreover, five color stairs from red and green to yellow showed only that the more colors are different, the smaller the visual evoked cortical potentials become. In addition electroretinogram recordings indicated that color-coded patterns behave in the same way as in visual evoked cortical potentials. The mechanism that causes the small color visual evoked cortical potentials may already be present in the retina. Color perception may be able to induce a suppression of responses for luminance contrast that appears to be formed already in the retina. Retinal responses were affected whether the stimulus field was color coded or not. Pattern electroretinograms appear to be more than the sum of local on and off responses.

Adult↗
PubMedDate not supplied

Efficacy of thyrotropin-releasing hormone in the treatment of cerebellar ataxia.

We report a 9-year-old girl with cerebellar ataxia in whom the administration of thyrotropin-releasing hormone was effective in the treatment of a prolonged neurologic deficit. Ataxia persisted 18 months after its acute onset of unknown origin. Concentrations of homovanillic acid and 5-hydroxy-indoleacetic acid in the cerebrospinal fluid were measured repeatedly. Changes in the 5-hydroxy-indoleacetic/homovanillic acid ratio were observed, suggesting that thyrotropin-releasing hormone improved symptoms by influencing serotonin metabolism in the central nervous system.

Cerebellar Ataxia↗
PubMedDate not supplied

Prevalence of senile dementia in a rural community in Japan: the Tajiri project.

Knowledge of the prevalence of dementia in different age groups is needed for the planning of a health policy. This study shows the prevalence of dementia and magnetic resonance imaging (MRI) findings in elderly people aged 65 years and over, living in the town of Tajiri in the northern part of Japan. They were shown by two cognitive screening tests, the Mini-Mental State examination (MMS) and the Dementia Screening Test (DST) and medical diagnosis. Two subject groups were assessed, those who completed both tests (Subjects I, n=2066) and those from among the 200 'MRI-administered subjects' who were interviewed and diagnosed (Subjects II, n=170). For Subjects I, there were 6.3 and 10.2% 'dementia range' according to the severe and mild criteria, respectively. As for Subjects II, 9.4% were clinically diagnosed as having dementia. They met the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria of probable Alzheimer's disease (AD) or possible AD with cerebrovascular disease. The estimated prevalence rate of dementia was 8.0%. Visual ratings of brain atrophy using MRI disclosed two distribution patterns. The 'continuous' pattern of the frontal and temporal lobes atrophy suggest that both are affected by the aging process, while a 'discontinuous' pattern of the hippocampal atrophy could indicate a pathologic background such as early changes of AD.

Journal Article↗
PubMedDate not supplied

Presence and quantification of neuropeptide Y in pulmonary edema fluids in rats.

The present study was undertaken to determine the contribution of neuropeptide Y to edema occurrence in neurogenic and hydrostatic pulmonary edema. To induce neurogenic pulmonary edema, fibrinogen and thrombin were injected into the cisterna magna; and to evoke hydrostatic pulmonary edema, saline was infused intravenously. Concentrations of neuropeptide Y in serum and edema fluid were measured using enzyme-linked immunosorbent assay (ELISA), which showed a mean value of 158 nM (95% confidence limit 124-202 nM) in the neurogenic edema fluid, significantly higher than that in the hydrostatic one. Using immunohistochemistry, fluorescent signals reactive to neuropeptide Y were found in the alveolar macrophages and edema fluid in case of fibrin-induced pulmonary edema, but were almost absent in hydrostatic edema and absent in normal lungs. Mean ratio of protein concentrations in edema fluid to that in serum was 74.9 +/- 0.9% in fibrin-induced pulmonary edema, being higher than that in hydrostatic one. From these results, we conclude that neuropeptide Y has a relationship to the high protein concentration ratio, i.e., to increased pulmonary vascular permeability, and consequently may contribute to the development of neurogenic pulmonary edema in rats.

Animals↗
PubMedDate not supplied

Role of vertical larynx movement and cervical lordosis in F0 control.

The role of vertical larynx movement in vocal frequency (F0) change has attracted the attention of many researchers. Recently, Hirai, Honda, Fujimoto, and Shimada (1994) proposed a mechanism of F0 control by vertical larynx movement based on the measurement of magnetic resonance images (MRI). In F0 changes, the larynx moves vertically along the cervical spine, which displays anterior convexity (lordosis) at the level of the larynx. Therefore, the vertical larynx movement results in the rotation of the cricoid cartilage and vocal fold tension changes. The present study reexamines the above mechanism based on a qualitative analysis of midsagittal MRI data using three male subjects with evident cervical lordosis. Tracings of the jaw, hyoid bone, laryngeal cartilage, and cervical spine were compared in high and low F0 ranges. In the high F0 range, the hyoid bone moved horizontally while the larynx height remained relatively constant. In the low F0 range, the entire larynx moved vertically, and the cricoid cartilage rotated along the cervical lordosis. These results indicate that the vertical movement of the larynx comprises an effective F0 lowering mechanism, and suggest that the human morphologies of low larynx position and spinal curvature contribute to voluntary use of the vocal function.

Cervical Vertebrae↗
PubMedDate not supplied

Experimental study on external tibial rotation of the knee.

Using biplanar roentgenographic photogrammetry, we investigated posterolateral rotatory instability of the knee joint both before and after sectioning of posterolateral structures, the posterior cruciate ligament, and the lateral collateral ligament. Fifteen fresh-frozen cadaveric knees were used. Compared with the intact state, sectioning of the posterior cruciate ligament alone did not increase the amount of external tibial rotation, but the axis of external tibial rotation shifted when the anterolateral bundle of the posterior cruciate ligament was cut. When the posterior cruciate ligament was cut after sectioning of the posterolateral structures and the lateral collateral ligament, external tibial rotation increased and the axis of external rotation shifted. The results demonstrated that sectioning of the anterolateral bundle of the posterior cruciate ligament is associated with a change in the location of the axis of tibial rotation. Therefore an isolated posterior cruciate ligament injury can alter the kinematics of the knee joint by changing the axis of external tibial rotation. The present results also demonstrate that the posterior cruciate ligament serves as a kind of secondary restraint to posterolateral rotatory instability in knees with injured posterolateral structures. Helical motion analysis using biplanar roentgenographic photogrammetry is a useful method for evaluating knee kinematics.

Aged↗
PubMedDate not supplied

Development of thermotolerance in hsp70 induction-defective mutant of NRK cells.

We investigated the relation between the synthesis of inducible form of heat-shock protein 70 (hsp70) and the development of thermotolerance using NRK (normal rat kidney) cells and their mutant cell line (39-1 cells). In NRK cells, hsp70 was clearly induced by conditioning treatments (42 degrees C for 2 h, 45 degrees C for 15 min or 100 microM sodium arsenite for 1 h). On the other hand, the induction of hsp70 in 39-1 cells was very low or not detectable by these treatments. Other high molecular weight hsps, hsc70 (constitutive form), hsp90 and hsp110 were induced in both cell lines. However, thermotolerance as defined by clonogenic survival was induced in both cell lines to a similar extent by the conditioning treatments. When cells were made thermotolerant by conditioning heating at 45 degrees C for 15 min, the inhibition of protein synthesis after challenge (second) heating was less in NRK cells than in 39-1 cells. This indicated that the extent of 'translational thermotolerance' was much higher in NRK cells than in 39-1 cells. From these results, it is suggested that the synthesis of inducible hsp70 is involved in the translational thermotolerance rather than the development of thermotolerance as defined by clonogenic survival.

Animals↗